Following criticism for a lack of action in the recent General Motors ignition switch defect, federal regulators aren’t holding anything back when it comes to keeping car manufacturers accountable for fixing safety issues on their vehicles in a timely manner. Or so it appears after the National Highway Traffic Safety Administration issued a hard deadline for Chrysler to answer for delays in fixing vehicles affected by a recall last year.

According to a report from the New York Times, NHTSA is giving Chrysler until July 16 to answer questions about why it is taking so long to produce trailer hitches to protect fuel tanks in more than 1.56 million Jeep SUVs recalled last year.

Last summer, the car manufacturer and NHTSA agreed to a remedy for the issue that left the vehicles at risk for catching fire. The repair involved equipping vehicles with a trailer hitch that could reduce the risk of fires.

NHTSA officials noted in the letter that Chrysler didn’t select a supplier for the new parts until December 2013, and that a purchase order wasn’t submitted until January. As of April, the parts are still not available.

The letter says in part that at the current rate of repairs, Chrysler would need 4.7 years to fix all of the recalled Grand Cherokees and two years to fix the Liberty SUVs.

Chrysler now has until mid-July to answer for its delayed process and why there was only one supplier hired to produce millions of parts.

According to the original recall notice [PDF] model year 1993-1998 Jeep Grand Cherokee and 2002-2007 Jeep Liberty vehicles were recalled because the rear-mounted fuel tank on the SUVs sat too low and were at risk for rear-end explosions.

The fix, which came after tense discussions between the two entities, was quickly criticized by consumer advocates. Their issue with the remedy rested in the fact that hitches had not traditionally been seen as safety devices, the Times reports.

During discussions last summer, Chrysler reportedly refused to crash test the remedy, so NHTSA took it upon itself to evaluate the hitch’s effectiveness.

This month, NHTSA released a crash reconstruction report [PDF] that found the extra part could, in fact, make a difference.

Adding the OEM hitch-receiver to the vehicles places additional structure behind and to the sides of the fuel tank. The added structure appears to reduce tank damage and fuel leaks in certain rear impact crashes.

Chrysler is currently under investigation by regulators for alleged ignition switch defects. The investigation was announced just three weeks ago and revolves around the company’s Dodge Grand Caravan, Dodge Journey, Chrysler Town and Country, Jeep Commanders and Jeep Cherokee models.

The affected vehicles may contain a defect that can cause the key to either be knocked or jostled out of the run position. This could then cause a loss of power to the steering wheel and brakes, as well as the disabling of the air bags in the event of a crash.

The issue with Chrysler comes just as regulators have been facing scrutiny for their lack of action after receiving a decade’s worth of reports on the General Motors’ ignition switch defect.

It took nearly 13 years, and at least 13 deaths before GM recalled 2.6 million cars because of the defect.